Military and law enforcement personnel as well as competitive shooters desire a loader that is convenient, compact, and quickly reloads a gun's magazine. There are many loaders that one can use to reload a gun. Many of these loaders hold ammunition cartridges and facilitate dispensing the cartridges into a gun's magazine. For example, there are many tube-type loaders that include a pusher for pushing the held cartridges into a rifle or shotgun's magazine tube. In addition, shotgun magazines can be reloaded using a box loader that includes a lever and an ejector. But unfortunately, most of these loaders are bulky and inconvenient to carry. Therefore, there is a need for a simple and convenient loader for reloading a gun's magazine.